Known inner paneling parts according to the state of the art are associated with disadvantages resulting from variation in airbag release momentum. In two- or multistage airbag systems, in the case of minor accidents, only one stage or even no stage is triggering, and a time delay in triggering a further stage is dependent upon the scenario. Very great differences between different possible opening impacts can be caused, by possibly considerable temperature dependent properties of, for example, a pyrotechnic filling device.
The inner paneling part, in the region of the passage opening, is typically designed to be sufficiently weak in order to ensure reliable breaking open by the opening airbag even in the case of an opening impact with as little momentum as possible. In accordance with the state of the art, this has the result that, when an airbag is deployed, only a very limited energy quantity which is extensively independent of the scenario can be absorbed by breaking open the inner paneling part. In the case of scenarios when an airbag opens with greater momentum, consequently a substantially smaller quantity of energy is absorbed by tearing open and folding back the covering than would be desirable with respect to the momentum of the opening impact.
As a result, material destruction caused by excess energy on the inner paneling part and adjacent components (in particular also on a vehicle windscreen which can consequently be broken) and a flight of particles which is associated therewith and endangers the vehicle passengers can scarcely be avoided or only with great complexity, such as for example, by complex reinforcement of the inner paneling part in regions which surround the passage opening. A rebound strap has been used to reduce in particular breakage of the windscreen by which a rapidly emerging airbag cover is stopped before impinging on the windscreen. However, it has been shown that these straps which are “slack” up to the extreme position during the explosion process allow unimpeded maximum acceleration of the airbag cover which in general is uncontrollable.
Basically it can be said that the opening behavior of an airbag flap/an airbag cover, according to the state of the art, must be directed or influenced by the type and intensity of the weakness of the flap or of the cover. The necessary level of force for opening the cover is limited by the characteristic values of the material of the weakened material which is used.